172 



TOTirALMATE SWIMMERS — STEGANOPODES. 



brown, this color sometimes overlyiuj,' tlie wliole lower surface, the white being mostly concealed. 

 " Bill light grayish brown ; the Ijare space aruund the eye pale grayish blue ; iris green ; feet dusky, 

 the narrow bantls of scutelhu pale grayish blue; claws grayish white" (Audubon). Nestling: 

 Entirely covered with very lluify yellowish white down. 



S. hassana. 



Total length, 37.00-39.00 inches ; extent, 68.50-74.00 ; wing, about 19.50 ; tail, 10.00 ; cul- 

 men, 4.00 ; tarsus, 2.25. 



Adult specimens in the collection of the National Museum vary greatly in the extent of the strip 

 of bare skin on the throat. In a male, not quite adult, from the Straits of Gibraltar, it reaches 

 almost to the jugulum ; but in others it does not extend beyond the throat. Perfectly adult indi- 



'II 



viduals have the tail entirely white, only the remiges being dusky. In less mature examples, 

 the tail, as well as the larger wing-coverts, are dusky. Still more immature specimens have the 

 back and scapulars mixed with dusky leathers. A young bird from Europe is very much darker- 

 colored than an American specimen, tlie lower surface being nearly uniform brownish gray, only 

 the concealed portion of the feathers white ; the white markings are almost entirely wanting on 

 the back and scapulars, and very minute elsewhere. 



